This invention relates generally to railyards and, more particularly, to monitoring train arrival and departure latencies for a railyard.
Railyards are the hubs of railroad transportation systems. Therefore, railyards perform many services, for example, freight origination, interchange and termination, locomotive storage and maintenance, assembly and inspection of new trains, servicing of trains running through the facility, inspection and maintenance of railcars, and railcar storage. The various services in a railyard compete for resources such as personnel, equipment, and space in various facilities so that managing the entire railyard efficiently is a complex operation.
In order to improve the efficiency of railyard operations, it would be useful for an automatic system to monitor the times at which trains enter a geographic area defining a railyard and, subsequently, leave the railyard. Determination of train entry and exit from the railyard is currently accomplished using automatic equipment identification (AEI) tag readers located at the geographic limits of the railyard. A train is comprised of pieces of rolling stock, such as one or more locomotives and one or more railcars, that are removably coupled together using mechanical coupling links. Typically, an AEI tag is attached to every piece of rolling stock in the train. The AEI tag includes coded information that uniquely identifies the piece of rolling stock to which it is attached. As a train enters a railyard, each piece of rolling stock passes an AEI reader, and the reader thereby collects identification information from the AEI tag. The AEI reader transmits RF energy towards a tag reading area and receives RF energy that is backscattered by an AEI tag situated within the tag reading area.
AEI tag reading systems are expensive and complicated to install. Electrical power must be routed to the tag readers, and the tag readers must be accurately aligned with respect to the set of railroad tracks that are to be monitored. Due to the amount of RF energy that must be transmitted by the AEI tag reader so as to obtain tag readings, some of this energy travels beyond the limits of the railyard where it may interfere with communications equipment. Accordingly, AEI tag reading systems are regulated by the Federal Communications Commission (FCC). A license must be obtained from the FCC in order to operate an AEI tag reading system within the United States.
The times at which trains enter and exit the railyard may create a potentially inaccurate picture of railyard operations unless additional information is acquired. An inbound train is considered to be “yarded” as soon as it enters the geographic limits of the railyard. However, due to congestion, crew availability, yard conditions, or other factors, it may not be possible to bring the train immediately into a receiving subyard so as to complete a train arrival process. Each individual railcar is delayed, thus impacting the performance metrics of the entire railyard and possibly causing delays in subsequent outbound trains from that yard. Accordingly, it would be desirable to minimize the time that elapses after a train enters the railyard, but before the train comes to a stop in a receiving subyard. It would also be desirable to minimize the time that elapses after a train enters a departure subyard, but before the train leaves the geographic limits of the railyard. These elapsed times, referred to as latencies, are not measured by existing automated railyard systems.
In addition to monitoring the times at which trains enter and exit a railyard, it would also be useful to monitor one or more sets of tracks within the railyard that may be occupied by a train. Track occupancy is currently monitored by installing wheel detectors along the tracks, or by installing track circuits over track segments. Both of these approaches require significant capital expenditure, installation labor, and electrical cable trenching which disrupts operations within the railyard. The foregoing considerations render existing track occupancy monitoring approaches undesirable and prohibitive. Accordingly, what is needed is a technique for monitoring train arrival and departure latencies which does not require deployment of equipment to individual tracks or individual locomotives.